Uncommon
by Cumberbatch Critter
Summary: He falls, and then he falls ill. [Castiel sick!fic. Multi!chap. Implied friendship only, but Destiel/Sastiel teases abounds. Rated T for Dean being Dean (language, innuendo, etc,etc).]
1. Chapter 1

**Uncommon**

"Well, what the hell do you want me to do, Sam? Bound onto hallowed ground and watch the bastard float around outside the circle of protection? Drink a beer and wave at it? Practice my miming skills?"

"I don't know, Dean, but it's _not a good idea_, though, you have to realize that!"

"Of course I realize that, Sam, but I don't see an alternative. If you've got any bright ideas, now _would_ be the time to throw them out there."

Castiel stretched his legs out, looking out the window. He was settled in and prepared for a total Winchester argument. He still wasn't sure why exactly this happened. Dean and Sam tended to... what was the expression... argue without really arguing. Butt heads. That was it. He'd heard them argue, for real, he thought, a few times... but he hadn't really wanted to get into the middle of that. Ever.

"I just think that we need to go into this with a little more planning, that's all."

"How much planning do we need?"

"I thought you didn't want us to go running in blindly," Sam retaliated.

"Well, we don't have a whole lot of choice, now do we? Not that what _I_ want seems to matter to you."

"Are you really bringing that up again? I already _told_ you-"

Castiel breathed in and let it out with a silent rush, exhaling through his nose. He leaned back in his seat and watched the empty landscape roll by outside of the Impala. They were moving fast today, on the way to some unidentified supernatural being that was murdering innocents in an Oregon town. The blurring motion of the landscape whizzing by was almost making him feel... strange.

"Well, don't talk our ear off back there. Got any bright ideas?"

It was definitely making his head hurt, at the very least, or maybe that was because the two brothers in the front seat had been arguing ever since they'd stepped out of the motel. Complaining. Whatever they called it. Castiel still wasn't entirely sure how loud noise, or continuous noise, or movement outside the car window could make his head hurt, but it was probably some... human mechanic. A human fault, one that shouldn't bother him in his state, but it was anyway. Or maybe he was just thinking too hard and was creating a potential psychosomatic ailment. There were still countless things that he didn't understand about the human body.

"Hell_o_. Wingman. Yeah, you."

Castiel looked up, meeting Dean's eyes in the rearview mirror. "I didn't realize that you were speaking to me."

"Well, I am," Dean said. "So, what's cooking in that brain of yours?"

Castiel blinked slowly. "Pain," he said truthfully.

Dean made a face. "What are you talking about, dude?"

"My head hurts. I guess what's 'cooking' is pain."

Dean's face in the mirror didn't change, but Sam twisted around in his seat. "_You've_ got a headache?"

"Oh, don't tell me _he's_ going to start with that."

"Maybe it's catching."

Dean huffed, grinning briefly. "Yeah, whatever. What's up, Cas?"

"Don't know." Castiel shrugged. "My head hurts."

"You prone to that? You get weird messages-from-the-Lord type headaches whenever he tried to contact you before?"

"That's not how it works," Castiel said, before raising his voice. "This is the first time I've experienced a, what did you call it, head-ache." Now that he thought about it, it wasn't only his head, but his stomach starting to have aches and pains, runners of jittery something-or-rather wrestling with his stomach. "I believe that I'm hungry," he added, although it wasn't exactly the same feeling, but that's what it must be, right? "Contemplating an attack on an empty stomach isn't doing good for any of us," he continued.

"Now, that's why I like this guy," Dean replied. "That's a good idea. There's a cheeseburger shack up the road here, I think I saw on the map. Double meat patty with cheddar, lettuce, tomato, two baked not toasted buns... maybe we'll find some toasted ones, too," he added, grinning first at Sam and then at Castiel.

Sam rolled his eyes, looking out the window. "Whatever."

"C'mon, Sammy. You know you want a big, _greasy_, burger and some soggy fries, complete with vinegar and ketchup on the side."

"You wouldn't believe me if I said I didn't, anyway."

"Fine, spoilsport. Cas? Sound good?" Dean asked, meeting his gaze in the mirror again. "Someone has to agree with me here."

"Sounds... good," Castiel replied. He wasn't sure that it did, actually, but his stomach was paining him for one reason or another. Maybe food would make it better, and a burger with fries and a slice of pie was the best remedy. Hopefully.

But then, cheeseburger and fries and pie later, maybe it wouldn't. And it didn't, because his stomach definitely wasn't feeling better. Now, it had an additional churning sort of feeling, something Castiel hadn't felt before and something he really wasn't particularly looking forward to feeling again. He absently pressed his arm against his stomach, only the barest level of Sam and Dean's conversation filtering through his consciousness. He could hear them talking, but he couldn't focus on what they were saying.

Mostly it was because of his stomach feeling strange, but his headache had intensified. There was throbbing behind his eyes that was reminiscent of being too tired, but he had slept last night, seven hours before Dean had grabbed his shoulder and shaken him awake. He felt like sleeping, though, despite having done nothing except sitting in the back seat of the car, and he had a strange desire to lean his head forward and rest it against the cold window.

He did not like the cold, that was another thing. He hadn't ever noticed before, but now Oregon in mid-November and having come from Michigan... this was his first winter as a human, and he hated it, especially now, when he was shivering in a booth at a burger shack. It was too cold, and yet, he still wanted to put his head against the cold window. He had an instinctual urge that it might help, but he didn't know why, or how.

"Castiel!"

Castiel's attention was jerked back to the conversation, his entire body flinching with the exclamation of his name. "What?"

"You're zoning out over there," Dean commented. "And you didn't order seconds, so now I'm seriously re-considering how dangerous this puppy is if you're holding back on lunch."

Castiel blinked tiredly. He felt disconnected with his own body. "I'm not hungry."

Dean raised his eyebrows.

"Hey," Sam interrupted, "you don't look so hot," he said, frowning as he looked at Cas. "Are you feeling alright?"

"Come on, Sam," Dean said, shoving fries into his mouth. "Cash ish Cash. He's not gonna jus' get shick-"

Castiel couldn't listen to whatever else Dean was saying with his mouth full of fries. His stomach was doing something definitively _not right_. Roiling and grumbling. He licked his lips, curling his fingers into his jacket. There was excess saliva in his mouth. He swallowed thickly.

"Yes, he is." Sam grabbed his shoulder. "Come on. Don't open your mouth," he advised, pulling him from the booth.

Castiel was about to question why he shouldn't, when his stomach jolted and something burning and acidic stung the back of his throat to fill his mouth. More human instinct clapped his hand against his mouth as Sam pushed him into the bathroom, Dean watching from the booth with his fork hovering above his food.

Castiel spent the next five minutes becoming intimate with the concept of vomiting, as well as the model of toilet used in the burger shack.

"How did you know he was going to hurl?"

"Because I spent enough time in college watching people throw up," Sam muttered. "Or trying not to."

"And failing when they puked down their fronts."

Sam laughed dryly. "In some cases, yeah."

Castiel pulled his head back and sat back. His legs curled into his chest and he wrapped one of his arms around them.

"You think it's the food? Not that I guess it matters. We already ate it." Dean shrugged. "Hey, I feel fine."

"No... Cas, did you feel sick before we ate? Stomach issues, you said you had a headache, umm, body aches, feeling hot or cold, anything?" Sam asked.

Castiel looked up from staring at a scribbled signature on the bathroom stall. "I had just assumed that my stomach didn't feel content because I was hungry, but the cheeseburger didn't help. The headache has intensified. It's unnaturally cold." He looked up at Sam and Dean. "You don't feel the temperature difference?"

Dean shrugged again. "I think it's comfortable, man. Better than that frozen wasteland out there."

Castiel found the energy to frown. Strange; Sam and Dean were as they usually were, but he wasn't even sure if he could manage to stand up from the bathroom floor of his own accord right now. His body felt weak, he could hear his heartbeat in his own head, and his stomach was still doing the rolling motion. He wasn't vomiting at the time being, but he certainly didn't feel any better for it. "What's happening to me?" he rasped.

Sam and Dean shared a look. It didn't lessen Castiel's apprehension to the situation.

"It kind of sounds like the flu," Sam said slowly.

Dean looked at Sam and then down at Castiel. "No." He looked back at Sam. "I mean... No. He's Cas."

"He's human," Sam pointed out.

Dean was frowning when he looked back at Castiel again. "How long you been sick, Cas? Is that why you've been quiet all morning?"

Castiel shrugged listlessly. He still didn't know what 'the flu' was. He didn't think it was a type of demonic possession, at least, not a type that he had heard of. Either way, he was becoming less and less inclined to continue the conversation, mostly because he felt worse and worse by the second.

"Shit."

"We gotta get him to a hotel, Dean. He's going to get worse before he gets better and dragging him out on the hunt isn't going to help."

"Great... Wait! I don't want him in the car if he's praying to the porcelain gods every three minutes." Dean looked down at him. "No offense."

Castiel just blinked up at him, slumping back against the stall. He felt his energy had been drained, like some invisible being was leeching away at the very essence of his life force. His eyes slipped closed of their own accord.

"We're just going to have to get a bin, or a bag, or something," Sam said. "I'll see what I can find around here. Stay with him." The bathroom door squeaked open, grating on Castiel's strangely sensitive eardrums, and footsteps retreated.

"Barf bags in my car..." Dean sighed thinly. "This is payback for the Hell thing, just so you know," he said. "We're so even for this."

Castiel tried to make an effort to look interested, or at least like he cared a _tiny_ amount. He barely managed to pry his eyes open, though, and the look on Dean's face as he looked down at him wasn't one Castiel was used to seeing. Usually he only ever looked at Sam with concern, and very rarely since Castiel had met them, anyway.

"Dude, you look like shit. You've barely been human two months and you're already down with it." Dean glanced at the bathroom door before sidling over, crouching down next to him. "I'm not exactly in best practice when it involves medicine and things, but Sam's practically a tottering old lady when it comes to colds and stuff."

"'Colds and stuff'?" Castiel echoed. "It is most definitely cold."

"You know what you told me before? Sometimes, things _do_ go right?" Dean grinned sardonically. "Now you're beginning to see why I didn't believe you."

Castiel just grunted, a sort of noncommental response, and let his eyes close again. The light was hurting his head.

Something warm brushed against his forehead. Castiel pulled his eyelids open again, quicker this time, to watch Dean press his hand more firmly against his forehead. Dean's hand was warm and, again, instincts took over, causing Castiel to lean over to press into Dean's touch.

"Take it easy there, man. Male-to-male caretaking only goes so far," Dean said, pulling his hand away. "Look too pleased and it starts to look a little pear-shaped to anybody else and, as of yet, I haven't done any batting for the other team. Butch or not," he muttered.

Castiel hadn't a clue what Dean was talking about, but he was acutely aware of the chilled feeling that swept across his body when Dean stepped away. Maybe it was the breeze from the movement, or maybe the frigid feeling that had settled into his bones. Something about the whole situation was unsettling.

He leaned over the toilet again as bile burned the back of his throat.

* * *

><p><strong>I actually... don't know a whole lot about Castiel. I've only seen up to 4x1, so I've known him for about five minutes. But I know he falls (I don't know the circumstances, and I'm trying not to spoil it, so please no spoilers!), and becomes human, and so... I'm writing a sickfic set in a season way ahead of where I actually am in the show. Hopefully my characterisation isn't <em>horrible<em>. I'm going off of clips I've seen and some fanfiction I've read from the fandom. xD**

**PLEASE no spoilers for SPN past 4x1!**

**I do not own _Supernatural_. Thanks for reading; stay tuned for chapter two soon!**


	2. Chapter 2

Castiel gripped the twin daggers tightly, curling his fingers around the intricately designed handles and pulling them close. His hands were bathed in blood. He pushed his fingers back through his hair with shaking hands, smearing blood and entrails, overly mindful of the knives and potential enemies nearby. He was, in all honesty, too tired for this battle, but, what was it Dean had said? The shit had hit the fan, big time.

A guttural growl to his left snapped his attention back to the battle and he twisted around, staggering slightly from the movement and the headache beneath his eyes, lunging forward to meet the adversary halfway.

Fighting as a human was always different. It wasn't something that he expected he would get used to anytime soon. Having a human vessel had taken a little time to adjust to, but then he had had few limitations to his form. He didn't eat, he didn't sleep, he didn't take mind to injury that would have killed a human being. But now, his balance was always more precarious, his reaction time was slower, and the scraping of talons against his arms shredded his skin like tissue paper and _hurt_.

He wouldn't get used to fighting as a human, or at least, he wasn't used to it now. And fighting while his head was pounding and he felt tired and unsettled was even harder than usual, but he would manage.

He thrust his dagger into the being's chest, twisting it ninety degrees and then pulling it free with a tearing squelch of skin and blood. He turned for the next one as it fell, criss-crossing the knives in both of his hands and jerking them into either side of the monster's throat.

"Right," he muttered, wiping his blades on his coat. "Time to find the Winchesters."

Not that it was difficult to find them. It never was. All Castiel had to do was look for danger and he would find them willingly present. And danger today was three against two, which meant regardless if Dean wanted to tackle them by himself, Castiel was bound to step in.

Fighting was exponentially easier when the world wasn't spinning, but he knew better: Hell didn't take a break, and there was no rest for the wicked. No matter how tired he might have been, the show went on.

"Cas, look out!"

Castiel turned in time to catch a glimpse of something fast and dark moving towards him. He stumbled back a step, completely off guard from parrying the last attack, knowing the timing involved in this attack would result in an injury for himself, unable to have the time to bring his blades up.

Something shoved him; he fell back hard, knives flying out from his hands.

"_Dean!_"

Castiel raised his head, looking up at what had shoved him out of the way; Dean. Dean, standing where Castiel had been previously. There was a gunshot and the adversary vanished into mist, but Dean staggered backwards. His hand went up to his chest; sticking out from his coat was the hilt of a knife.

"Dean!" Sam yelled, ending the last of their enemies before dropping the pistol to run over.

Dean's fingers curled around the hilt for a moment before he staggered back again, collapsing down onto his knees.

Castiel moved without conscious thought, catching Dean as he fell. "Dean?" he asked quietly. His chest felt weird, a dull ache spreading throughout his skin, which was _not right_ because Dean had been the one who had been stabbed...

Sam crashed to his knees next to them, grabbing Dean's shoulders. "No, no, no, no, no, Dean! Not again, no, Dean! _Dean!_"

* * *

><p>Castiel woke with a strangled gasp, sitting bolt upright in the cheap motel bed. He was tangled in the blankets and soaked with sweat, trapped somewhere between what he'd just seen and the fact that he was in the motel, very much not on the battlefield, and Sam was sitting at the table ten feet away, watching him closely.<p>

"Cas?"

Castiel looked over at Sam, swiping his tongue over his dry lips, trying to unstick his tongue from the roof of his mouth. He couldn't seem to manage.

Sam straightened up, putting the book he was paging through down. "Hey, Cas. Talk to me?"

Castiel shook his head slightly, trying to push away the blankets. They were tangled around his limbs and he couldn't untangle himself, much to the dismay of his stomach. He was starting to feel a little panicky.

"Okay, okay," Sam said, launching out of the chair. "Just take it easy." His hands pulled back the blankets much easier than Castiel was managing. "You were just having a night... mare."

Castiel had already sprinted across the room to the en suite at this point, flinging open the door before his stomach could rebel onto the carpet.

"Oh, don't knock or anything-" Dean started, but it was at this point that Castiel threw up, and Dean finished his sentence with a "_Oh, that's great_".

The shower curtain pulled back. Castiel glanced up when he was no longer occupied, squinting up at Dean's water-streaked face. "What?" he muttered. His throat felt raw and his mouth was burning.

"You are just a bucket of sunshine," Dean said, pulling the curtain closed. "Don't flush the toilet."

Castiel chose not to respond, but slumped forward to rest his forehead against the toilet seat.

"Isn't being human great?"

Castiel wanted to retort, perhaps with a touch of irritation, but he didn't have the energy. Instead, he just huffed, and wrapped his arms around the toilet.

"We're so... disposable. Vulnerable," Dean continued, mock cheerfully. "You used to be a messenger of God, and now look at you."

Castiel's fingers constricted around the toilet seat. "Dean."

"Yeah, Cas, buddy?"

"Shut up."

Dean just laughed at him. "Don't worry, Cas. It's usually short-lived. Intense, but short-lived. Sam and I've both had it. It's a pain in the ass, but you'll live."

"That remains to be seen," Castiel muttered.

Dean snorted. The water clicked off and there was some rustling before Dean stepped out of the shower, towel wrapped around his hips.

Castiel ended up staring mostly at his bare feet, not bothering to raise his head from the toilet seat. Dean was right. There was something horribly ironic about this, being draped over the toilet with the flu.

"How the mighty have fallen."

Castiel managed a weak glare. "Shut. Up," he repeated, trying to hit the tone that Dean and Sam used when they said it. He didn't know if he managed; he hadn't ever uttered the command before this.

Dean grinned down at him before turning away to the sink, stepping over Castiel's legs in the cramped bathroom.

Castiel peeled his face away from the seat, sitting up slightly. "I had a dream about you," he said critically, looking up at Dean.

"Maybe not the best thing to admit, Cas." Dean spit toothpaste into the sink. "I don't want to hear about your kinky sex dreams, especially if they involve me. Some things I just don't need to know."

Castiel shifted uncomfortably. The toilet paper dispenser was digging into his back. "You died," he said bluntly.

Dean raised his eyebrows. "Really? Was it that rough?"

"We were not having sex," Castiel replied tiredly. "We were on a hunt. You stepped in when I was about to be attacked."

"Oh." Dean spit again and rinsed, rubbing the back of his hand against his mouth. "Well, anything's possible." He held his hand down to Castiel. "Come on, get off the floor. You don't even want to know what's down there."

And he didn't really care, to be honest, but he didn't say anything, just reached up to take Dean's hand. He let him pull him up, struggling to maintain his balance and find his feet, only to fail spectacularly when darkness tore across his vision.

"Hey! Cas!"

Castiel scrabbled for purchase on anything, the wall, the sink, but he ended up latching onto Dean's arms and staggering sideways into his chest. His legs felt wobbly and the world was looking the way that the way that the washing machine did when he stared through the little glass door. Dean was shower warm beneath Castiel's goosebump-covered-body and he pressed instinctively closer despite how he already felt too hot on the inside. How could the human body feel hot on the inside but be cold on the outside?

"Sammy!" Dean yelled, hooking his arms under Castiel's. "Little help in here!"

Castiel sighed heavily and let his eyes stay closed. He couldn't open them right now, anyway. There were still many limitations to the human body that he was unaware of.

He was vaguely aware of Dean's hand against his sweat-soaked back. He thought he heard Dean saying something along the path of _"We'll get you better, Cas, don't worry"_, but then again, he couldn't be sure. Human illness did weird things to the senses, and Dean wasn't particularly prone to outbursts of brotherly compassion in the first place, let alone exclamations of fallen angel compassion.

He definitely, probably misheard him.

But then he was half asleep, and as sick as a human, and it really didn't matter in the long run to begin with.

* * *

><p><strong>Buckets and buckets of sunshine.<strong>

**Sorry for the chapter delay - got waylaid by Godstiel in S6 and then crazyCas in S7. S8's bringing the feels back, though. :P I do not own ****_Supernatural_. Thanks for reading!**


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